I can't figure out HOW to get into it or where to put the entry within that file.
It's a text file which you can edit using a text editor such as nano, vi, vim, gedit, kate etc. On command line you can do:
Normally you don't have to edit /etc/fstab as it's done automatically during installation. Using this file kernel mounts filesystem at different mount points mentioned in each line of the file.
Entries or fields in '/etc/fstab' file are separated by spaces or tabs. You can read up on 'fstab' here
or just type 'man fstab' on command line.
You can find out if a file is a text/ASCII file or not, by checking it with 'file':
Edit: '/etc/fstab' can only be changed by 'root' user. When you ask question please mention which distro you are using, it just helps to give an answer that best suits you.